1. Technical Field
The present invention relates to a semiconductor memory apparatus, and more particularly, to a nonvolatile memory apparatus including a flag cell in a redundancy memory cell area.
2. Related Art
In general, a semiconductor memory apparatus is classified into a volatile memory apparatus and a nonvolatile memory apparatus. In the volatile memory apparatus, stored data is lost when power is off. However, in the nonvolatile memory apparatus, stored data is retained although power is off. The nonvolatile memory apparatus includes various types of memory cell transistors. The nonvolatile memory apparatus may be classified into a flash memory apparatus, a ferroelectric RAM (FRAM), a magnetic RAM (MRAM), a phase change RAM (PRAM) and the like according to the structure of the memory cell transistor.
Of the nonvolatile memory apparatus, the flash memory apparatus is mainly classified into a NOR flash memory apparatus and a NAND flash memory apparatus according to a connection state of a memory cell and a bit line. The NOR flash memory apparatus has a structure in which two or more memory cell transistors are connected to one bit line in a parallel manner. Thus, the NOR flash memory apparatus has superior random access time characteristics. The NAND flash memory apparatus, however, has a structure in which two or more memory cell transistors are connected to one bit line in a serial manner. Such a structure is called a cell string, and one bit line contact is required per one cell string. Thus, the NAND flash memory apparatus has superior characteristics in terms of the degree of integration.
In the nonvolatile memory apparatus, defects may occur due to various factors in a fabrication process. When defects occur in is a peripheral circuit for driving a memory cell array of the nonvolatile memory apparatus, the nonvolatile memory apparatus may not normally operate. However, when defects occur in a part of memory cells of the memory cell array, it is possible to replace a failed memory cell with a redundancy memory cell. To this end, the nonvolatile memory apparatus include redundancy memory cells.